Protective device for parallel feeders.



No. 771,346. PATENTED 00514, 1904.

' L. WILSON. PROTECTIVE DEVICE FOR PARALLEL FEEDBRS.

APPLICATION FILED NOV. 2, 1903.

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WITNESSES INVENTOR.

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' ATTORNEY.

UNITED STATES Patented October 4, 1904.

PATENT OFFICE.

' LEONARD IVILSON, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR ,TO STANLEYELECTRIC MANUFACTURING COMPANY, OF PITTSFIELD, MASSACHUSETTS, ACORPORATION OF NEWV JERSEY.

PROTECTIVE DEVICE FOR PARALLEL FEEDERS.

SPECIFICATION forming part of Letters Patent No. 771,346, dated October4, 1904.

Application filed November 2, I903. Serial No. 179,492. (No model.)

To (all whom it may concern:

Be it known that I, LEONARD WILSON, a subject of the King of England,and a resident of Pittsfield, Massachusetts, have invented certain newand useful Improvements in Protective Devices for Parallel Feeders, ofwhich the following is a specification.

My invention relates to protection for parallel feeders, and isespecially applicable to high tension alternating current systems,although it is not limited in application to such systems. WVhere anumber of feeders are connected in parallel both at the generating andat the receiving end, it is essential in order to secure safe andcontinuous operation that any one feeder if it becomes shortcircuitedshould be disconnected from the healthy feeders both at the generatingand at the receiving end; otherwise, even though the faulty feeder isdisconnected at the generating end, the short-circuit will be maintainedthrough the healthy feeders, which are connected to the fault at thereceiving end. Heretofore protective devices for systems employingparallel feeders have been devised which depend for their operation uponthe relative potential of the parallel feeders, the lowering of thepotential on the grounded feeder being taken advantage of in apparatusdesigned to cut it out. On systems of high potential such protectivedevices are very expensive, since they involve the use of potentialtransformers or other apparatus which must be designed to withstand thepotential of the system.

The object of my invention is to provide means for protecting parallelfeeders Which shall be equally applicable to high and low tensionsystems and which while positive and eflicient in action shall be simpleand economical to install.

In the accompanying drawing, A represents an alternating-currentgenerator connected to the station bus-bars 1 2.

B C represent two feeders connected in parallel through fuses or otherprotective devices b c to the station bus-bar l.

D represents a feeder of the opposite polarity connected to stationbus-bar 2. Although D is represented by a single line in order to 5avoid complication of the drawing, it will be understood that aplurality of parallel feeders may be used for both polarities of thetransmission system and that the line D may represent a reduplication ofthe feeders B C. 5 5 B, C, and D represent the receiving ends of thesefeeders. B and C are connected in parallel to the receiving bus-bar 3,and feeder D is connected to the receiving bus-bar of opposite polarity4. E E represent the series transformers, the primaries of which areinserted in feeders B and C, respectively. The secondaries oftransformers E E are connected to the solenoids F F. The cores orplnngers ff of solenoids F F are carried at opposite ends of the pivotedbar Gr, which is held normally in the position shown in the drawing bythe springs g g. If, however, the current in one feeder exceeds that inthe other, the pull upon one of the solenoids ff will be greater thanthe pull on the other. Pivoted bar G will consequently be rotated. BarCr carries the contacts H H, which when the bar is tilted make contactwith the stationary contacts 70 lo, respectively. 'hen either of themovable contacts H H is in contact with its stationary contact 72 or it,as the case may be, a circuit is completed through the battery or othersource of current I and one of the solenoids J or J. Solenoids J and o Joperate as tripping-coils for the switches K and K, which are adapted toopen the circuit of feeders B and C, respectively.

The operation of the system is as follows Assume the system to besupplying current to the receiving bus-bars 3 a and whatever translatingdevice may be connected thereto. Now suppose feeder C becomesshort-circuited by a ground or other disturbance on the line whichconnects it to feeder D. The fuse or 9 other protective device a willopen the circuit of feeder C at the generating end. Current will alsoflow through feeder B to the receiving end of the line and back throughfeeder C to the fault. The primary of series transformer E will now becarrying a larger current than the primary of series transformer E,since the primary of transformer E is carrying not only theshort-circuit current, which flows through transformer E, but also theload-current, which flows to the bus-bars 3 4. Consequently solenoid Fwill exert agreater pull upon its core than solenoid F. The left-handend of bar G will be depressed and contact H will engage stationarycontact h. The circuit will then be completed through the source ofcurrent I and solenoid J Switch K will accordingly be tripped and willfall, opening the circuit of feeder C and making engagement with thestationary contact 71:. Stationary contact k is crossconnected to feederB, and consequently switch K places the primary coils of the seriestransformers E E in parallel in the feeder B. The pull of the solenoidsF F is now equalized and bar Ur returns to its central position underthe influence of springs g 9. Thus the faulty feeder is cut out both atthe generating and receiving ends and continuity of service ispreserved.

I have shown my invention as applied to alternating-current systems,since it is especially applicable to high-potential lines, andaccordingly I have shown the differential device connected to thefeeders through series transformers. It will be understood, however,that I am in no way limited to alternating-current systems. My inventionis equally applicable to parallel feeders carrying direct current.Moreover, I have shown my invention as applied to a single-phasealternatingcurrent system. It is evident that it may be applied withequal facility to an alternatingcurrent system of any number of phases.Accordingly I do not desire to limit myself to the particularconstruction and arrangement of parts here shown, since changes thereinwhich do not depart from the spirit of my invention and which are withinthe scope of the appended claims will be obvious to those. skilled inthe art.

Having thus fully described my invention, I claim as new and desire toprotect by Letters Patent 1. In combination, parallel feeders, a movablemember, opposing windings adapted to pull said member in oppositedirections and arranged to be energized by the currents in therespective feeders, and switches controlled l by said member and adaptedto open the circuit of the feeder carrying the smaller current.

2. In combination, parallel feeders, a difi'erential electromagneticdevice responsive to a difference in the amounts of current-flow in saidfeeders and independent of the relative directions of said currents,andaswitch adapted to be operated by said device and to open the circuitof the feeder carrying the smaller current.

3. In combination, parallel feeders, magnetwindings arranged to beenergized by the currents in said feeders, a movable member comprisingtwo magnetic cores and adapted to be drawn in opposite directions bysaid windings, and a switch adapted to be operated by said member.

at. In combination, parallel feeders, magnetwindings arranged to beenergized by the currents in said feeders, a movable member adapted tobe drawn in opposite directions by said windings, and a switch adaptedto be operated by said member and to open the circuit of a feeder and toconnect its magnet-winding to another feeder.

5. In combination, parallel feeders, magnetwindings arranged to beenergized by the currents in said feeders, amovable member comprisingtwo magnetic cores and adapted to be drawn in opposite directions bysaid windings, a local circuit arranged to be closed by the movement ofsaid member, a tripping-coil in said local circuit, and a switchoperated by said tripping-coil.

6. In combination, parallel feeders, an elec troresponsive device, meansfor causing the currents in said feeders to produce opposing forces insaid device, and a switch controlled by said device and arranged to openthe circuit of the feeder carrying the smaller current.

7. In combination, parallel feeders, overload cut-outs at the generatingend of said feeders, and a differential device at the receiving end ofsaid feeders arranged to open the circuit of the feeder carrying thesmaller current after the operation of one of said overload cut-outs.

Signed at Pittsfield,Massachusetts, this 28th day of October, 1903.

LEONARD WILSON.

itnesses:

L. A. HAWKINS, R. E. HAYNES.

